Circuit breaker



A. F. KOLB ET AL CIRCUIT BREAKER 4 Sheets-Sheet l Nov. 19, 1957 Filedoct. 16, 1955 APT/,'02 F) /COLB fue,

Nov. 19, 1957 A. F. KoLB ET A1. 2,813,951

CIRCUIT BREAKER Filed Oct. 16, 1953 4 Sheets-Sheet 2 A1- Ansv Nov. 19,1957 A. F. KoLB ET AL 2,813,951

' CIRCUIT BREAKER Filed oct. le, 1955 4 sheets-sheet FIO 1% I4 62 7e,

/NvENToRs 4 THEODOP f7 P05/NG ,/COLB Fl 7 l ARTHUR F CIRCUIT BREAKERFiled 0013. 16, 1955 4 Sheets-Sheet 4 INVENToRs A ,Q TNI/,Q E KUL BryHfoof f7 P05/N6 A 'QRNEY CIRCUIT BREAKER Arthur F. Kolb, Milwaukee,

Whitefish Bay, Wis., assignors to Cutler-Hammer, Inc., Milwaukee, Wis.,a corporation of Delaware Application October 16, 1953, Serial No.386,436 12 Claims. (Cl. 20u-116) and Theodore F. Rosing,

This invention relates to circuit breakers, particularly small circuitbreakers adapted for use as motor starters.

The principal object of this invention is to provide a simple reliableand inexpensive circuit breaker of this character.

A further object of this invention is to provide a circuit breaker ofthis character which is easy to assemble, requires a minimum number ofworking parts, is fully protected .against deleterious etects fromsparking and external dust and dirt particles.

A still further object of this invention is to provide a circuit breakerof `this character which does not require detrimentally sharp hammerblows to open the circuit.

In obtaining these objects the circuit breaker is provided with thefollowing general characteristics: The movable contact ycarryingbridging members are loosely mounted on a contact bar which is slidablyguided in the base and cover forming the circuit breaker housing. Suchbridging members are spring biased toward closed circuit position andwith the contact bar move back and forth in a path substantiallyperpendicular to parting line between cover and base. This facilitatesassembly of the circuit breaker. The contact bar is moved toward theclosed end of the cover to open the normally closed contacts by amanually controlled over-center spring action carried in the base. Thisaction is installed in the base by the simple expedient of axiallysliding its main pivot into a bearing in the base while such action ismomentarily held in place. The action includes a contact operating leverwhich engages with the contact bar to move it to opened position. Suchlever has an overload bar which in overload conditions is engageable byan overload lock and reset lever also included in such action. Theselevers, a spring support and a manually operated lever are all mountedon the same pin in such action. While there is a slight tolerance builtinto the mechanism to provide for wear of the contacts, this is notsufficient to impart a hammer blow in the opening of the contacts.Instead the overcenter spring action imparts a positive andinstantaneous opening to the contacts without the necessity of damaginghammer blows which soon wear and break down such small lightlyconstructed vcircuit breakers. The base and the cover completely enclosethe contacts and all -operating members, except the handle of themanually operated lever, to protect them from dust and dirt and to keepharmful sparking fully shielded.

For a more detail description of this invention reference should be madeto the following description of a specic embodiment read in connectionwith the accompanying drawings, in which:

Figure l is a top plan View of a circuit breaker embodying the presentinvention with the manually operated lever in or position;

Fig. 2 is a sectional view taken on the line 2 2 of Fig. l;

2,813,951 Patented Nov'. 19, 1957 htice tFig. 5 is a sectional viewtaken on the line 5 5 of Fig. 3;

Fig. 6 is a sectional view taken on the line 6 6 of Fig. 3;

Fig. 7 is a sectional view taken on the line 7 7 of Fig. 5;

Fig. 8 is a sectional View taken on the line 8 8 of Fig. 5; and f Fig. 9is an exploded prospective view of the circuit breaker shown in Figs.1-8 (incl.)

The circuit breaker illustrated in the drawings is a multiple polestarter rated at approximately l horsepower, single phase on and 230volts. Completely assembled it is approximately 11/2 inches wide, 21/2inches long and 2 inches high. Such small circuit breaker has a base 1l)and a cover 12 formed of molded insulating material which are secured toprovide a housing for the complete circuit breaker operating mechanismexcept the handle of the manually operated lever. On a ilat portion ofthe base `10 facing the cover 12 there are mounted xed contacts 14 intothe threaded supports of which are threaded exterior terminal screws 16.Between these contacts is a groove 18 for guiding the contact carrier.Slots 20 transverse to such groove guide the linger of the contactoperating lever. A projection 22 on the base 10 houses the thermalrelease assembly. A rectangular hole 24 accommodates the handle of themanually operated lever and provides shoulders limiting the extrememovements of such handle. The over-center spring action is held in thebase 10 during assembly of the circuit breaker by having an extendingend of the pivot of such action project into a bearing 26 in such base.Opposite this bearing is a cylindrical groove 27 which cooperates with asimilar cylinder groove in the cover to form the other bearing for suchpin.

The cover 12 has a recess 2S which accommodates the swinging elements ofthe over-center spring action. At the bottom of this recess is a groove30 which guides the end of an overload lever. The right-hand wall ofsuch recess has a semi-cylindrical groove 32 (see Figs. 4 and 8) whichprovides an abutment for the spring of the over-center spring action.Adjacent to the recess 2S are a pair of spaced recesses 34 (see Figs. 6and 7) terminating in cylindrical wells 36 which provide operating spacefor the contact bridging members and their compression springs. Slots 38cooperating with the grooves 13 in the base 1l) provide the completeguide for the contact bar. A semi-cylindrical bearing 46 in the coverl() (see Fig. 5) cooperates with the semicylindrical bearing 27 in thebase 10 to form the outer bearing for the main pivot of the over-centerspring action.

The movable contacts of the circuit breaker are mounted on a pair ofbridges 42 apertured to loosely slide on tongues 44 on a contact carrier46. The carrier 46 is made of insulating material such as melamine andis slidably guided in the groove 18 and slots 38 to simultaneously movethe bridges 42 in the recesses 34 with the contacts thereon in alinementwith respective pairs of the fixed contacts 14. The bridges 42 arecontinually urged toward the closed circuit position shown in Figs. 3, 6and 7 by compression springs 48. lt is relatively simple to assemble thebridges 42, carrier 46 and springs 48. The springs 48 are seated in thewells 36 of the cover. The bridges 42 are placed on the tongues 44 andthe contact carrier 46 iitted in the groove 18 of the base 10. When thecover 12 is placed on the lbase 10, the springs 48 will be properlycompressed. The contact carrier 46 has a centrally located slot 50 whichengages a finger on the contact operating lever to aid in electing itsmovement toward circuit opened position.

The over-center spring action includes a manually operated lever 52 towhich is pivoted by a single main pivot 74 a spring support 70, acontact operating lever 82, and an overload and reset leverV 90. Anover-center spring 76 extends between the bridge of the spring support70 and a spring yoke 62 pivoted to the manually operated lever 52. Themanually operated lever S2 is made of insulating material and has a handengageable iinger which in the assembled condition projects outwardly ofthe housing through the hole 24. A pair of spaced shoulders 54alternatively engage the ends of hole 24 to establish the off and onposition of the lever 52. A pair of trunnions 56 with bearings 58therein are spaced by a groove 60. The latter slidably guides the springyoke 62 pivoted to the lever 52 by a pin 64 iitting in an elongatedbearing 66 in the lever 52 and passing through a hole 68 in such springyoke. The spring support 70 is U-shaped and has a connecting bridge anda pair of legs terminating in apertured ends 72. These ends straddle thetrunnions 56 with the apertures aligned with bearings 58 and mounted onthe main pivot 74. The tension spring 76 has one end anchored to thebridge of support 70 and its other end engaged in a hole 78 in the yoke72. This yoke has an arcuate slot 80 which permits it to swing about thepin 64 without interfering with the main pivot 74. Such linkage willcause the spring support 70 to move back and forth between its limitposition of Fig. 2 and its limit position of Fig. 3 upon swinging thelever 52 back and forth between its open circuit position of Fig. 2 andits closed circuit position of Fig. 3. Such motion after dead center isreached is very rapid.

In normal operation the motion of the spring support 70 is transmittedto the contact carrier 46 by the contact operating lever 82. This leverhas a pair of supporting legs straddling the spring support 70 andpivoted on the main pivot 74. Such contact operating lever 82 has anextending linger 84 slidable in the slots 20 and seated in the slot 50of the contact carrier 46. The bridge of lever 82 hasy an arcuate recess86 which iits around the spring 76 to permit the clockwise edges of thebridge to be engaged by the legs of the spring support 70 in the Ynormally operating ott position of the circuit breaker of Fig. 2. The`contact operating lever 82 also has `an overload bar 88 which isengaged by the overload and reset lever 90 when the latter is `releasedupon an overload.

The overload and reset lever 90 has a main bridge with spaced supportinglegs 92 straddling the contact operating lever 82 and pivoted on themain pivot 74. The lever 90 also has a spring anchor 94 with an outersupporting leg 96 also pivoted on the main pivot 74. A tensionedoverload spring 98 extends from the anchor 94 to a pin 100 secured inthe base 10. A locking arm 102 formed as part of the lever 90 has aspring finger 104 normally engaged with a ratchet 106 of a thermalrelease assembly 108. Such assembly is well known and is shown anddescribed in Patent No. 2,261,632 issued November 4, 1941 for ElectricCircuit Mechanism. The ratchet 106 is normally held against rotationuntil the heater coil 108. connected to a terminal 110 and the adjacentterminal 16, melts the eutectic solder upon occurrence of an ove-rload.The ratchet 106 will then rotate and release the overload and resetlever 90 which will under iniiuence of spring 98 operate to open thecircuit. The terminal 110 is carried in a plate 112 to which isthreadedly fitted a terminal 114 for external connection.

To assemble the over-center spring action, the spring yoke 62 is placedin the groove 60 and pin 64 inserted in bearing 66 through hole 68. Thenthe spring 76 is secured to the anchor 78. The spring support 70,contact operating lever 82 and overload and reset lever 90 are theniitted over the trunnions S6 and the main pivot 74 inserted through themand the bearings 58 until its inner end (left as viewed in Fig. 9) istlush with the inner of the legs 92. The spring 76 is then connected tothe support 70. The action is assembled as a unit into the base 10 withthe handle of the lever 52 projecting out of hole 24. The main pivot 74is then moved inwardly, so that its inner end slides into the bearing 26thus holding the action in place. After the contact bar 46 and spring 98are assembled in the base 10, the cover 12, with bridges 42 and springs48 in place, is placed on the base 10 and secured by screws 116 whichare threaded into mounting strips 118.

Starting with the circuit breaker in the oli position, shown in Figs. iand 2, assume that the handle of the operating lever 52 is swung fromthe o position to the on position shown in Fig. 3. During the first partof such movement the contact operating lever 82 holds the spring support70 in the position shown in Fig. 2. As the pin 64 moves clockwise aboutthe main pivot 74, such pin, pivot and anchor 78 approach a position ofalignment with the central axis of spring 76. Slightly before suchalignment position is reached the force exerted by springs 48 issufficient to overcome the then opposing force of spring 76, andmovement of the contact carrier toward closed position results in theforced movement of lever 70 through the aforementioned aligned positionto its opposite extreme position shown in Fig. 3. During theaforementioned movement pin 64 moves to engage with the other end ofslot 66 in lever 52.

Starting with the parts shown in the on position of Fig. 3, movement ofoperating lever 52 in the counterclockwise direction to the olf positionshown in Fig. 4 will cause pin 64, pivot 74 and anchor 78 to be broughttoward the aforementioned alignment position. During such movement pin64 moves from the right end to the left end of slot 66 thereby providinga slight lost motion action, offsetting any retarding tendency caused bythe speed or manner of movement of lever 52. Spring support 70 is heldagainst the groove 32 as shown in Fig. 3 during the initial part of suchmovement. As the alignment position is passed, the tension of the spring76 moves spring support 70 rapidly in the clockwise direction from suchposition, to the position shown in Fig. 2. The legs of the springsupport 72 will Contact the bridge of operating lever 82 and swing itclockwise to the position shown in Fig. 2 with a rapid motion butWithout hammer action. The nger 84 instantly depresses the contact bar46 with the consequent opening of the contacts as the effective force ofspring 76 is considerably greater than the combined effective force ofsprings 48.

With the circuit breaker in the normally on position shown in Fig. 3, anoverload will release the ratchet 106 and the overload and reset leverwill instantly pivot under the influence of spring 98 to the positionshown in Fig. 4. Its arm 102 will engage the overload bar 88 and swingthe contact operating lever 82 to the circuit open position shown inFig. 4. This takes place without any interference to or from themanually operated lever 52, the over-center spring 76, and the springsupport 82. After the overload has been removed and the solder in thethermal element hardened, the circuit breaker may be reset. This isaccomplished by swinging the manually operated lever 52 from the onposition of Fig. 4 to the off position of Fig. 2. This movement causesthe lefthand lower edge of such lever to engage the bridge of the lever90 and swing such lever counterclockwise to carry the arm 102 to theposition shown in Fig. 2, sothat the spring 104 will again engage withthe ratchet 106 and hold such lever with energy stored in spring 9S.Lever 90 in so moving disengages from lever 82, and the lattermomentarily freed rotates a slight Iamount in the counterclockwisedirection thereby permitting contact carrier 46 to move a slight amounttoward contact closed position. During the aforementioned resettingoperation, spring support 70 is caused to snap over-center to theposition shown in Fig. 2, and in so doing engages with lever 82 to drivethe latter in the clockwise direction before it can move freely anyappreciable amount in the counterclockwise direction.

It will be observed that because lever 90 can move lever 82, to contactopening position independently of lever 52 and spring carrier 70, thatthe circuit breaker is of the trip-free type, that is to say, thecontacts cannot be closed by movement of lever 52 to on position,following resetting operation of the latter if the thermal element hasnot rehardened.

While there is shown a particular embodiment of this invention, manymodications may be made land it is contemplated that the followingclaims cover any such modifications as fall within the spirit and scopeof this invention.

We claim:

1. A circuit breaker comprising a movable contact constantly biasedtoward closed circuit position, an insulating contact bar having aprojection along which said contact is movably guided, a housingproviding guides for said bar, a lever engageable with said bar, anover-center spring action manually operable to one position to move saidlever and thereby overcome said bias to move said contact `to opencircuit position and manually operable to a second position to permitsaid contact to move to closed circuit position under its bias, andmeans responsive to current overload to move said lever yand operatesaid contact to open circuit position independently of said overcenterspring action.

2. The combination according to claim 1 in which said housing includes abase and a cover and said guide directs said bar to movement in a pathsubstantially perpendicular to the parting line between said cover andbase.

3. The combination according to claim 1 in which said action includes amain pivot having limited axial movement and said housing has a bearingreceiving an end of said pivot following axial movement thereof.

4. A circuit breaker comprising an insulating base having an inner atsurface, a bearing in said base having an opening in said surface, asemi-cylindrical groove in said base aligned with said bearing, -amovable over-center spring action in said base and guided by saidsurface, a main pivot for said action having one end projecting intosaid bearing and the other end resting in said groove, and a cover forsaid circuit breaker having a semi-cylindrical groove cooperable withsaid iirst groove to form a bearing for said other end of said shaft,said second groove having an abutment engageable with the end of saidpivot to prevent axial displacement thereof.

5. A manually operable over-center spring action for the movable contactof a circuit breaker comprising a main pivot, a manually operated leveron said pivot, a contact operating lever swingably mounted on saidpivot, said lever having a contact operating finger and an overload bar,a spring support swingably mounted on said pivot engageable with saidcontact operating lever, a spring acting between said spring support andsaid manually operated lever, and an overload lever swingably mounted onsaid pivot and operable when released to engage said overload bar andoperate said contact operating lever without movement of said springsupport.

6. The combination according to claim 5 in which said overload lever hasa portion engageable by said manually operated lever to operate saidoverload lever for resetting thereof.

7. The combination according to claim 5 in which said overload lever hasa spring anchor integral therewith and pivoted on said pivot.

8. A circuit breaker comprising a movable contact constantly biasedtoward closed circuit position, a slidable contact bar, a manuallyoperable over-center spring action, a contact operating lever engageablewith said bar, and a spring support positioned closely adjacent saidlever in circuit closed position and immediately engageable with saidlever as said over-center spring action is operated to circuit openposition.

9. The combination according to claim 8 in which said over-center springaction has a manually operated lever having a pivotal axis and anelongated bearing spaced from said axis, there being a pin in saidbearing, and a spring anchored on said pin and said spring support, saidpin sliding from end to end of said bearing as said action passesover-center to eliminate possibilities of wavering movement due tomanual sluggishness at the overcenter position.

10. A circuit breaker comprising an insulating base having an openingtherein, a groove in said base, a slot in said base transverse to saidgroove, a fixed contact on said base adjacent said groove, a contact barslidably guided in said groove and engageable with a movable contact tomove such movable contact to circuit open position, an over-centerspring action mounted in said base having a manually operated leverprojecting through said opening, said action including a contactoperating lever having a finger guided in said slot and engageable withsaid bar to move said bar to circuit open position, an insulating coverfor said base forming therewith an enclosure for said over-center springaction, a recess and well in said cover, a movable contact operable insaid recess, and a spring in said well for normally biasing said movablecontact into engagement with said fixed contact.

11. A circuit breaker as claimed in claim 10 in which said over-centerspring action includes a swingable spring support for moving saidcontact operating lever to circuit open position, said cover having aportion for engaging said spring support in the circuit closed positionthereof and holding said support closely adjacent said contact operatinglever so that upon operation of said over-center spring action saidsupport will engage and move said contact operating lever without ahammer blow.

12. A circuit breaker as claimed in claim 10 in which said over-centerspring action includes a spring biased swingable overload lever havingan arm engageable with said contact operating lever to move said leverto circuit open position, there being a groove in said cover for guidingthe end of said arm.

References Cited in the file of this patent UNITED STATES PATENTS2,166,545 Getchell July 18, 1939 2,343,264 Platz Mar. 7, 1944 2,418,537Wood Apr. 8, 1947 2,611,055 Webster Sept. 16, 1952 2,657,289 Wolfe etal. Oct. 27, 1953 2,660,642 Warren Nov. 24, 1953 2,703,350 Rosing Mar.1, 1955 FOREIGN PATENTS 455,204 Great Britain Oct. 15, 1936

